The electrophotographic image forming apparatus is an image forming apparatus for forming an image on a recording medium in accordance with an electrophotographic image forming method. Examples of the electrophotographic image forming apparatus may include an electrophotographic copying machine, electrophotographic printers (such as a laser beam printer and an LED printer), a facsimile apparatus, a word processor, etc.
In the image forming apparatus such as the electrophotographic copying machine, the laser beam printer, etc., a latent image is formed by selectively exposing an electrically uniformly charged surface of a photosensitive drum to light and is developed with a developer to form a developer image. Then, the developer image is transferred onto a recording medium to effect image recording. In such an image forming apparatus, the developer is required to be supplied every time the developer is used up. Here, a developer supply container for supplying the developer to the image forming apparatus is roughly classified into a so-called simultaneous supply-type developer supply container which supply the whole amount of developer contained in the developer supply container to a developer receiving container of a main assembly of the image forming apparatus at the same time and a stationary-type developer supply container which is mounted into the image forming apparatus main assembly, left standing as it is, and gradually supplies the developer to a developing apparatus until the developer is used up.
Particularly, in recent years, from the viewpoints of contamination during supply of the developer and operability, many proposals for the latter stationary-type developer supply container have been made. In the case where a developer in an image forming apparatus is consumed, a developer supply container (hereinafter also referred to as a “toner cartridge”) is replaced by demounting it from the image forming apparatus and mounting a new one into the image forming apparatus, so that (fresh) toner is supplied to the image forming apparatus.
The toner as the developer is very fine powder, so that there has arisen such a problem that the toner scatters from a minute spacing between constitutional parts due to operational vibrations or the like during a toner supply operation, thus contaminating a user or surrounding parts with the toner. For this reason, such a method that a developer supply container is mounted inside a main assembly of image forming apparatus and toner is discharged little by little from a small opening has been proposed and put into practical use. In such a method, it is difficult to discharge the toner naturally by the action of gravity or the like, so that the image forming apparatus is generally provided with any toner stirring conveyance means.
Further, below the toner cartridge (developer supply container), the image forming apparatus is provided with a buffer portion, as a toner containing portion, for temporarily storing the toner. Inside the buffer portion, a metering screw for stirring the toner and feeding a predetermined amount of toner corresponding to a degree of rotation and a conveyance screw, disposed downstream from the metering screw, for conveying the toner by being rotated always during recording (image formation) are disposed so as to supply a necessary amount of toner to a process cartridge.
In the case where all the amounts of toner in the toner cartridge are discharged into the buffer portion to empty the toner cartridge in the above described image forming apparatus, the image forming apparatus detects the empty of the toner cartridge and provides notification, to a user, that the developer supply container should be replaced with new one. In accordance with this notification, the user removes the (old) empty developer supply container from the image forming apparatus and inserts a new developer supply container into the image forming apparatus in place of the empty developer supply container, so that the image forming apparatus is capable of further continuing an image forming operation.
Japanese Laid-Open Patent Application No. 2000-162861 has disclosed, as an example of a conventional developer supply container, such a constitution that a shutter of a developer supply container is opened and closed through a rotational force transmission member provided in a main assembly of an image forming apparatus, as shown in FIGS. 13 and 14.
Referring to FIG. 13, an image forming apparatus is provided with an open/close portion 501 at a side surface of an main assembly 500 of the image forming apparatus, so that a developer supply container (toner cartridge) 600 is mounted and demounted from the side surface of the image forming, apparatus. The toner cartridge 600 has, as shown in FIG. 14(a), a developer discharge opening 601 (FIG. 15) sealed or covered with a container shutter 602. The container shutter 602 is constituted so that it is not readily opened even when a user rotationally moves it in a simple one direction outside the main assembly, thus preventing toner from contaminating surrounding parts or portions due to erroneous leakage.
Further, as shown in FIG. 14(b), when the toner cartridge 600 is mounted into the main assembly 500 of the image forming apparatus, a driving force is transmitted from a driving force transmission portion 603a of a knob 603 provided to the toner cartridge 600 to a driving force receiving portion 602a of the container shutter 602 through a driving force relay portion 502 provided in the apparatus main assembly by rotationally driving the knob 603 of the toner cartridge 600, so that the container shutter 602 is moved apart from a toner discharge opening. Incidentally, in FIGS. 14(a) and 14(b), the toner cartridge 600 is depicted upside down for convenience of explanation. Accordingly, during actual mounting of the toner cartridge 600, an upper surface of the toner cartridge 600 shown in these figures is located at a lower surface thereof in the actual mounted state.
Further, as shown in FIG. 15, a buffer portion 503 of the apparatus main assembly 500 is provided with a developer receiving opening 504 opposite an apparatus shutter 505 for preventing contamination when the toner cartridge 600 is not mounted. The container shutter 602 and the apparatus shutter 505 are engaged with each other by mounting the toner cartridge 600 into the main assembly 500 to perform an open/close operation in an integrated state. Accordingly, by rotating the knob 603, the container shutter 602 and the main assembly shutter 505 can be opened simultaneously to cause the toner container 600 and the buffer portion 503 to communicate with each other to create a toner suppliable state. Further, when the toner container 600 is demounted from the apparatus main assembly 500, the toner container 600 is pulled out after the container shutter 602 and the main assembly shutter 505 are closed by rotating the knob 603. When the toner container 600 is capable of being demounted in such a state that the main assembly shutter 505 is not completely closed, the developer receiving opening 504 is placed in an incomplete closing state, so that contaminant or the like enters the buffer portion. As a result, there is a possibility that a photosensitive drum is damaged, to adversely affecting an image.
In the constitution as described above, as a driving force transmission mechanism, gears are ordinarily used. For this reason, an idling period is generated by the time rotation members start to transmit a driving force to each other when the container shutter is rotated by the knob from the opened state toward a closing direction. This is because there is backlash between the gears. More specifically, with reference to FIGS. 16(a) to 16(c), when the knob 603 is rotated, a gear of the driving force transmission receiving portion 603a (having teeth K, L) is rotated in a direction of an arrow E to rotate a gear of the driving force relay portion 502 (having teeth M, N) in a direction of an arrow G. As a result, when the container shutter 602 is opened, as shown in FIG. 16(a), tooth K and tooth M are stopped in a contact state due to sliding resistance such a reaction force from a seal in contact with the container shutter 602 under pressure. This contact state is retained during recording (image formation) but when the knob 603 is rotated in an opposite direction in order to close the container shutter 602 to rotate a gear of the driving force transmitting portion 603a in a direction of an arrow F, only the gear of the driving force transmitting portion is rotated to start separation of the teeth K and M from each other as shown in FIG. 16(b). Thereafter, as shown in FIG. 16(c), tooth L and tooth M come in contact with each other. During this period, the driving force cannot be transmitted from the driving force transmitting portion 603a to the driving force relay portion 502. By further rotating the driving force transmitting portion 603a in the direction of the arrow F, the driving force transmitting portion 603a starts to rotate the gear of the driving force relay portion 502 in a direction of an arrow H.
With respect to the above constituted toner container 600, as shown in FIG. 14(b), three or four drive gears are ordinarily provided. At an engaging portion between respective gears, loss by the backlash is caused to occur to lead to a non-negligible deviation as a whole. As a result, even when the knob 603 is returned to the original position, such a phenomenon that the container shutter 602 and the main assembly shutter 505 are not returned to their original positions is caused to occur. For this reason, the knob 603 provided to the toner container 600 has been conventionally constituted so that the container shutter 602 and the main assembly shutter 505 can be restored to their original positions by providing the knob 603 with such a structure that it can be much rotated in a shutter close direction compared with a shutter open direction.
Incidentally, demands for a further reduction in mounting space of the main assembly of image forming apparatus and an improvement in operability have been still increased, so that arrangement of consumable articles such as the developer supply container (toner cartridge) and a removal direction of the developer supply container are of increasing importance. For the reduction in mounting space, it is effective to set the removal direction of the consumable article and an access direction into the main assembly such as a housing open/close direction during clearance of paper jam as uniform as possible. As a result, the apparatus main assembly is provided with a side surface free from an open/close door, so that there is no need to ensure a space for opening and closing the door at the side surface at the time of mounting the image forming apparatus, thus being very effective for space saving. Further, a single function printer having no image reading mechanism is improved in operability by setting the consumable article removal direction as an upward direction of the main assembly since the image reading mechanism covering an upper portion of the image forming apparatus is not employed.
In view of this point, e.g., as shown in FIGS. 2(a) and 2(b), it can be considered that an image forming apparatus is provided with a toner cartridge cover 23 at an upper surface thereof and a toner cartridge 31 is mounted from above the image forming apparatus. With respect to the toner cartridge 31, it can be considered that an unshown container shutter and an unshown apparatus shutter are opened and closed by rotationally driving a handle 36 in place of the knob 603.
Even in the case where such a constitution is employed, similarly as in the case of the conventional toner container 600 inserted from a side surface of the apparatus main assembly, there arises the backlash problem. For this reason, it is necessary to adopt such a constitution that the toner container 31 cannot be removed until the main assembly shutter and the container shutter are closed with reliability. Particularly, with respect to the main assembly shutter, there is a possibility that the deviation of the shutter resulting from the backlash is accumulated when the shutter is closed plural times in repetitive use even when the deviation by one closing operation is within an allowance. For this reason, during repetition of replacement of the toner container 31, there are possibilities that the developer receiving opening cannot be finally closed and that the container shutter and the main assembly shutter cannot be engaged with each other in order to ensure conjunction of the container shutter with the main assembly shutter. Accordingly, return of the main assembly shutter to the original position should be observed carefully.
Further, in order to realize size reduction of the image forming apparatus as a whole, when the respective toner containers 31 are disposed closely, a size of the handle 36 is restricted, so that an amount of rotational movement of the toner container is also restricted. For this reason, in order to ensure the same amount of rotational movement for each mounting of the toner container 31, it is necessary to engage the toner container 31 with the gear drive mechanism of the apparatus main assembly while retaining an initial position of the handle 36. Accordingly, it is necessary to dispose an axial direction of the handle 36 to be perpendicular to the insertion direction of the toner container 31 and dispose the drive mechanism of the apparatus main assembly to be substantially under the toner container 31 (downstream in the insertion direction of the developer supply container). In that case, a force is exerted on the gar drive mechanism in such a direction that the gears are separated from each other, i.e., that the toner container 31 is pulled out. Thus, it is necessary to provide such a constitution that the toner container 31 can be held simply with reliability. Incidentally, the conventional toner container 600 had the insertion direction, thereof into the apparatus main assembly, identical to the rotational axis direction of the knob 603, so that it was possible to easily hold the toner container 600 with respect to a force for separating the gears from each other, i.e., a force exerted in a vertical direction of the rotational axis of the rotation member by holding a guide rail 604 of the toner container 600 with a main assembly guide 506.
When the above described opening and closing mechanism of the shutters and the holding mechanism of the toner container 31 are intended to be realized as an automatic control mechanism, an increase in production cost is caused to occur. Further, when the respective operations for opening and closing the shutters and for holding the developer supply container are intended to be performed manually, the number of steps for performing replacement operation of the developer supply container is increased, so that there is a possibility that the increased steps lead to a poor operability.